strongroom
noun
- a room for money or valuables specially constructed to be fireproof and burglarproof
Wiktionary
noun
Etymology: strong + room
- A strongly built room or vault where valuables may be safely stored.
“All of Sellafield is in a holding pattern, trying to keep waste safe until it can be consigned to the ultimate strongroom: the geological disposal facility (GDF), bored hundreds of metres into the Earth’s rock, a project that could cost another £53bn.”